European Patent Application EP-A-0 033 094 (partially equivalent to U.S. Pat. No. 4,450,164) describes imidazo[1,2-a]pyridines which in the 8-position carry an aryl substituent which is preferably a phenyl, thienyl, pyridyl, or chlorine-, fluorine-, methyl-, tert-butyl-, trifluoromethyl-, methoxy- or cyano-substituted phenyl radical. As aryl radicals of particular interest, EP-A-0 033 094 mentions the radicals phenyl, o- or p-fluorophenyl, p-chlorophenyl and 2,4,6-trimethylphenyl, of which the radicals phenyl, o- or p-fluorophenyl and 2,4,6-trimethylphenyl are particularly preferred.--European Patent Applications EP-A-0 204 285 (equivalent to U.S. Pat. No. 4,725,601), EP-A-0 228 006, EP-A-0 268 989 (equivalent to U.S. Pat. No. 4,831,041) and EP-A-0 308 917 (equivalent to U.S. Pat. No. 4,920,129) describe imidazo[1,2-a]pyridines which in the 3-position carry an unsaturated aliphatic radical, in particular a (substituted) alkynyl radical.--European Patent Application EP-A-0 266 890 describes imidazo[1,2-a]pyridines which are substituted in the 8-position by an alkenyl, alkyl or cycloalkylalkyl radical.